January, 1919.] SOD, TILLAGE AND FERTILIZERS. 19 



Plot 9 which is treated with more nitrogen than the other plots 

 has made the greatest average growth for the ten-year period, 

 being 85 per cent greater than the sod plot, and 14 per cent greater 

 than Plot 5, the strongest of the unfertihzed plots. We should 

 not assume that excessive growth is desirable and that the suc- 

 cess of the work could be measured by the greatest growth ob- 

 tained for there are indications that more growth is being made in 

 some plots than is desirable. 



The growth of the trees is feeble in 1918 following the severe 

 winter which reduces the average somewhat. 



Trunk Growth. 



Since 1913 the growth of the trees has been measured by the 

 diameter of the trunks as well as by the length of the annual ter- 

 minal growth. The method employed is to select a spot on the 

 trunk at a height of two feet from the ground and mark it with 

 white paint, and also select a spot at right angles to the first one, 

 likewise marking with paint so that the measurement can be taken 

 each year at the same point. A caliper is used in making the 

 measurements and the two diameters averaged for each tree each 

 season, thus giving a better figure than if just one measurement 

 were taken. 



Table No. 6 shows the average diameter in inches of the trees 

 in each plot in 1913 and the average increase which each plot has 

 made. Here again we find Plot 9 and also Plot 8 showing the 

 highest average growth for the five-year period which is 83 per 

 cent greater than the sod plot, while it will be recalled that in 

 twig growth Plot 9 averaged 85 per cent greater than the sod 

 plot for the ten-year period. 



